Safety brake loading device for rubber and plastic mills and the like



July 4, 1950 K. B. CONNER 2,513,453 SAFETY BRAKE LOADING DEVICE FORRUBBER AND PLASTIC MILLS AND THE LIKE Filed Sept. 15, 1948 4Sheets-Sheet 1 ff z/zefl/fl @mzer 5y kw Amiga,

July 4, 1950 K. B. CONNER 2,513,453

SAFETY BRAKE LOADING DEVICE FOR RUBBER AND PLASTIC MILLS AND THE LIKEFiled Sept. 13, .1948 4 Sheets-Sheet 2 K. SAFETY BRAKE LOADING DEVICEFOR RUBBER AND PLASTIC MILLS AND THE LIKE B. CONNER July 4, 1950 4Sheets-Sheet 3 Filed Sept. 13, 1948 4 Sheets-Sheet 4 Filed Sept. 13.1948 hmtsw Q MX h.

m m w M w WNQ Qua/Hag fi [bl/21267" dy $55M? Patented July 4, 1950 3 THELIKE RUBBER .AND PLASEIC -MILLS AND Kenneth- B. (Jenner; Rivertom N; :1;assignor to "f WiIIiamR; Tliropp &' Son's CoQ-Tre'nton;N:-J.,

a corporation ofNew Jersey I i-npmieatiafi September 13; 1948: SerialN61 49,026 '2 Claims. (owe-2) This invention relates to *an -improved'br'ake "and brake--loading mechanismdesigned to be 7 used on heavymachineiy having large iniunning rolls, for example rubber-=and*plasticmills, and calenders.

111 the operation of-inr'u'nning rolls and similar"rolling*macliinery'where it is nec'essarythat the worker positioned inclose proximity to" the inrunning rolls, there is always the danger"that the worker may-fal1 onto the rolls in "such away that serious'physical-injury results. Safety de- "-vices for i'nrunningrolls havebeen used for many years but with varying degrees of success.Such-devices include 1.' Externally contractingband brakes operated '"by'a 'weighted lever arm, retained by-a latch, which inturn' may e either1 mechanically released or'releasedbydeener'gization of a solenoid.2.-'Al'sp'ring-set 1 solenoid-operated shoe or disc brake. 3. Electricbraking-systems comprising a multiplicity of solenoid-operatedcontactors. -Exainp1es of l the" first two classes above; are shown "inthe following patents issued to J. W. ThroppfNo'. 1,447,105, N0.1,490,'788,'1 IO. 1,621,442. A particular disadvantage of theniecha'nical'or falling weight type of"b'rake=1oa3dingdevice resides-in"the factthat the rolls cannot always be stopped in time toavoidserious-injury. Further- -n'1'0re',the' severityof injury' increases indirect proportion to the time required 'toobtain maximum braking effort.Due to the relatively great length of timerquired to apply brakingeffort, it is' necessa'ry to' utilize-the maximum braking'torqueobta'inable to stop the rolls in the time permitted byvarious-safety codes, and as a result extreme stresses" are setup =inthevarious structural membersof the mill. It has'be'en' foundin yearsofpractice'thatthe mill operatorfbeing avvare'of the factthat the safetydevice' may 'not stop' the rolls sufficient time to avoid injury, willattempt to pull' his handor arm out of the rolls before tripping thebrake'in the event of an" accident. C l'onsequ'ently, many severe"injuries" have-" resulted"which could have been avoided'sdlelyor inpa'rt if the operator'knew positively that the rolls couldbe' stopped'intime to avoid serious injury.

"The disadvanta ge'of the third class of braking systemsinen'tionedabove, resides in the fact that maximum braking torques are limited bythe inherent electrical characteristics of the motor'to a value "less'th'an tha't obtainable by" a device 'cons'trueted in accordance withthe present inven designed for 'driving themill under ndrm'alf con- 'dtiorisof operation;1tis*'only half thej'size requi'red "to top the rollsin" the' requir'ed time. Therefore, 'if the proper motor is installedori'the m'illynO adequatesafety feature is 'pres'entjaiid-on "the otherhand, if a -sufiioientlylargemotor is "used to' provide-adequate safety;the EfillII' may of Y the mill-and f the'cost arepracticallyprohibitive. I havefoundthat my imp'roved brakefas described herein,will 5 "stop inrunning *rolls-conjsistently-{i 40 %-bfthe"distance ofperipheral-Toll "travelas'fce m'pared to the falli'ng' weig'ht typeofdevice disclosecl'the above Thropppa'tents; In "addition the-presentdevice utilizes onlyapproxi- I 'matly 46% of the maximum torduer'equiredby the falling weight type of brake. Ano herserious objection tdthefallingweight'device reierred to in the above 'citedpatents, residesiii-the fact-that *constant vibration of the mill tends to wear thelatch action even'whe'nthe brake 'its'elffis not *u's'ed=,"- so thatsuch abrake "in-time *fails' to functio'n properly. '---'-A-disadvantage'ofany braking'*-device "dependent' on the operation {of-j one or "moresolenoids resides'intlie fact that residua1- magiietism -may preventfree niovement of the se1eiioid armature," thereby causing" an excessive"time delay in the application oithe' braking-load; The time-"normallyrequiredto actuate a 'singl'e'j soleiioid is n'ot lss than .05 SeG'OIid'even-when the meel'ianismis fu-netioning properly.

Since {electric -braking systems of "the dynamic, regenerative} orplugging types utilize a plurality of successively actuated'solenoidsfthetime'-re- *quired to appl the braking "load with'such esystem insofar as 'thefis'olehoidsare concerned tion'i In'bther-words,'if"the motor is properly' will "be -roughly the -n'umberof isolenoid's'm'u1tiplied by .05 secondfevenwhen 'thefsystem is functioning properly.*In 'addi'tionto the "time reduired-to actuate aplurali ty oi solenoids,adelec- I 3 Modern industrial safety requirements as well as safetylegislation have posed a practical problem which is not easy of solutionin View of the fact that the speed and size of mill rolls, as well asthe number of rolls, have been greatly increased in recent years.Obviously, the problems involved in stopping small rolls at slowspeedwithin a required peripheral distance are increased by a geometricalprogression rather than an arithmetical progression as the size andspeed increases. This trend to constantly higher speeds and larger,heavier machines in order to obtain greater production per unit hasrendered all existing brake systems obsolete. Regardless of safetyregulations, it is essential for the general safety of the operator thateven large machines be equipped with safety devices providing themaximum freedom from injury.

In addition to the increased speeds and sizes referred to above, theproblem is also complicated by the fact that the braking surface mustnot be subjected to contamination from the various chemicals, dusts andabrasives used in the rolls.

Externally contracting shoe-type brakes and disctype brakes '(whichprovide neither fan action nor proper sealing) are not capable ofconsist- 'ently dependable operation under such operating conditions. Myconstruction permits the use of an internal expanding automotive typebrake which may be properly sealed against the entrance of foreignmaterial, thereby avoiding glazing of the braking surface. This resultfollows because not only is the surface enclosed but the fan action ofthe rotating brake drum tends to prevent foreign material fromcollecting in and around the brake assembly.

A primary object therefore, of my invention is to provide a brakingmechanism for inrunning .rolls which will completely stop the rolls witha minimum of peripheral roll travel.

.A further object is to provide a device Of the character describedwhich will completely stop heavy inrunning rolls in a minimum of timeand with a minimum of peak braking torque.

A further object of the invention is to provide a reliable brakingsystem for rubber or plastic mills which will not be adversely affectedover long periods of disuse of the brake.

A further object of the invention is to provide a hydraulically actuatedinternal expanding brake 1 and a spring-loaded plunger adapted toactuate a hydraulic cylinder connected to the brake.

Further objects will be apparent from the specification and drawings inwhich:

Fig. 1 is a side elevation of a rubber or plastic mill incorporating myinvention;

Fig. 2 is a side elevation of the structure of Fig. 1 as seen at 2-2 ofFig. 1;

Fig. 3 is a detail plan of the driving connections of the device,showing a typical location of the brake element;

Fig. 4 is a side elevation on an enlarged scale of the brake loadingunit;

. Fig. 5 is a front elevation of the structure of Fig. 4;

Fig. 6 is a fragmentary sectional detail as seen at 6-6 of Fig. 4; and

Fig. 7 shows the loading curve of my improved braking system as comparedwith the loading curve of the previously used falling weight type ofbrake loading device. I

The invention comprises essentially the provision of an internalexpanding brake connected to vthe drive shaft of the mill. The brakeloading mechanism comprises a heavily loaded, light- 43 is retracted bymeans of lever 5|.

weight plunger adapted to actuate a hydraulic master cylinder when theplunger is released by means of a trigger.

Referring now more particularly to the drawings, Figs. 1-3 show aconventional rubber or plastic millhaving a pair of inrunning rolls l0and II journaled in housings |2 and I3. The roll shafts l4 and I5 carryat one end a pair of spur gears l6 and I! which mesh with each other.Roll shaft I5 is extended at the opposite end of roll l0 and carries alarge bull gear l8 driven by pinion gear l9 mounted on gear box 20. Anelectric motor 2| is connected to gear box 26 through the brake assembly22 which is of the conventional internal expanding automotive typecommonly supplied for trucks and buses. The brake drum 22a is mounted ona coupling 22b and the backing plate 23 is mounted on a pedestal 24 andis provided with a hydraulic connection 25 to which is attached an oilline 26. It will be understood that the brake assembly may be mounted inany; convenient location. on the mill and should be adapted .tocooperate with any high speed shaft in the drive.

The brake loading mechanism designated generally 30 is mounted on thebed plate in such a position that it is conveniently accessible to thesafety bars 3| and 32 attached to side arms 33 and 34 which are in turnattached to a central rock shaft 35. Shaft 35 is pivotally mounted inbrackets 36 and 31. A cross arm 38 is rigidly attached to one extremityof rock shaft 35ias shown in Figs 1 and 2. p

The loading device 30 comprises a casing 4|] (Fig. 4) which is ofcylindrical configuration and is provided'with end plates 4| and 42, thelatter of which may be an integral part of the casing 40. A plunger 43is journaled for-axial movement in end plate 4| by means of bushing 44,and in end plate 42 by means of bushing 45. A piston 46 is mounted onplunger 43 and is adapted to abut shoulder 41 on the plunger. Sixhelical compression springs 48 are adapted ,to be compressed betweenpiston 46 and end plate 4|. The number of springs and their size will,of course, depend upon the requirements of the particular installation.Springs .48 are maintained in position by means'of aligning rods 49, 49threaded into end plate 4| and extending through piston 46. End plate 4|carries an ear 50 which pivots the resetting lever 5|. The cylindrical40 is provided on its upper portionwith aflange 52 on whichis mounted ahydraulic master'cylinder 53. Plunger 43 extends axially through endplate 42 and is provided with a pair of holes drilled at right angles toeach other in the plunger extremity.

The innermost hole accommodates a pin 54 which secures a bifurcatedextremity of link 55. Link 55 is pivoted to webs 56 and 51 (Fig; 5) bymeans of pins'58, 59 and link 60. The upper extremity of lever 55 ispinned to the eye 6| of master cylinder plunger'62' by means of pin 59'.V

A sear lever 63 is pivoted to plunger 43 by pin 64 and tolink 65 bymeans of pin 66. Link 65 is in turn pivoted to ear 6! on end plate '42by means of pin 68. The opposite end of sear lever 63 is provided with abeveled sear 69 adapted to be engaged by trigger 16 when the plungerTrigger lever H which carries trigger H1, is pivoted to cylinder 40 bymeans ofscrew 12 and bossl3; Trigger lever H is also spring-loaded bymeans of helical spring 14 suspended from bracket 75-. Arm 76 limitsupward pivoting movement of trigger lever ll to; prevent the sear .65from over,-

riding trigger Ill. The opposite end of trigger lever extends beyondtrigger 70 and is provided with a hole H to which cables 18 and 19 areconnected, as shown in Fig. 2. The cables 18 and 19 are secured at theextremities of cross arm 33 by means of clevises 80, 80. End plate 42 isprovided with a pair of internally biased guides 8|, 8| which facilitatesetting of sear lever 63.

The opposite end of plunger 43 is provided with an adjustable collar 82which is engaged by bell crank 83 on setting lever A switch 84 isoperated by contact roller 85 and lever 86 in a manner to be more fullydescribed hereinafter. In operation, the safety bars 3|, 32 and crossarm 38 are retained in a normally horizontal position as shown in Figs.1 and 2, by means of a spring-loaded detent 81 mounted in boss 88 onbracket 36 and cooperating with a notch or groove 89 in arm 38. In theevent of an emergency, the operator of the mill has only to move one ofthe safety bars 3| or 32 a distance of approximately 2" in order toraise trigger lever H by means of arm 38 and cables 18, I9. This actioninstantly disengages sear 69 from trigger 10, thus permitting plunger 43to be ejected with great force and extremely high acceleration throughend plate 42. Lever 55 pivots on pins 58 and 59 to compress fluid incylinder 53 and apply the brake, thus stopping the rolls within afraction of a second. At the same time, axial movement of plunger 43operates switch 84 to deenergize the main motor circuit (not shown)thereby stopping the motor.

When it is desired to reset the brake loading device, it is onlynecessary to raise the lever 5| until the trigger re-engages sear 69 onsear lever 63.

Referring now to Fig. 7, the relative efficiency and extremely desirableresults achieved with my brake system can be best illustrated bycomparing the time and braking torque with the formerly used fallingweight device. The curves in Fig. 7 have been calculated and plottedfrom test data obtained on a 22" x 22" x 60" rubber mill. Curve A ischaracteristic of such a falling weight device and shows that the brakeloading time is not less than .8 second. Likewise, maximum brakingtorque will not be achieved until nearly one second after the safety barhas been actuated. The braking torque for curve A reaches a maximum ofabout 2500 K. Curve B is illustrative of the braking system of myinvention. It will be noted that maximum torque of about 1200 K. isapplied to the brake in less than .03 second from the time that thesafety bars are actuated. The terrific stresses produced on the mill andits associated structure are greatly reduced because the maximum torqueis less than half that of curve A. The most striking difference however,resides in the fact that with my improved device the rolls may becompletely stopped in less than half a second, which in the test mill isequivalent to A" of roll travel, so that it is the combination of thepeculiar characteristic of my improved braking and brake loading devicewhich has enabled consistent stopping of the mill rolls in 40% of theprevious best results and with only 40% of the maximum torque.

It will be understood that the above data refer to a 22" x 22" x 60"mill. Naturally, the requirements of larger or smaller mills to achievecomparable results will dictate certain modifications in the brakeloading device, all of which are within the scope of thepresent'invention.

I have therefore provided a braking system which enables a mill havinghigh inertia to be stopped in a comparatively short time. High stressesin the mill are avoided and the device is positive as well as foolproof.Although the total amount of work done in stopping the mill rolls doesnot vary, with other factors being equal, the characteristics of theloading curve obtained with my device are such that braking torque isapplied nearly instantaneously and maintained at a suificiently high butconstant level to bring the mill to a complete stop within less thanhalf a second. My brake system permits utilization of a standardinternal expanding hydraulic brake unit in a mill, thus enhancing thedesirable characteristics of the installation and it will be appreciatedthat the device is relatively simple and inexpensive to manufacture.

Having thus described my invention, I claim:

1. A quick-acting brake loading unit comprising a hollow casing, a pairof end plates for said casing, a plunger axially journaled in said endplates, a piston mounted on said plunger inside said casing, a,plurality of aligning rods mounted in one of said end plates andextending axially through said piston, a plurality of helicalcompression springs surrounding said aligning rods and adapted to becompressed between the piston and one of the end plates, a sear leverpivotally mounted on the opposite end plate, a pivotal connectionbetween the sear lever and one end of the plunger, a spring-loadedtrigger for said sear lever, a limit stop for said trigger, an actuatinglever pivoted to the case and to the plunger, and a hydraulic mastercylinder mounted on the case and operatively associated with theactuating lever.

2. A quick-acting brake loading unit comprising a hollow casing, a pairof end plates for said casing, a plunger axially journaled in said endplates, a piston mounted on said plunger inside said casing, a pluralityof aligning rods mounted in one of said end plates and extending axiallythrough said piston, a plurality of helical compression springssurrounding said aligning rods and adapted to be compressed between thepiston and one of the end plates, a scar lever pivotally mounted on theopposite end plate, a pivotal connection between the sear lever and oneend of the plunger, a spring-loaded trigger for said sear lever, a limitstop for said trigger, an actuating lever pivoted to the case and to theplunger, a hydraulic master cylinder mounted on the case and operativelyassociated with the actuating lever, and means for moving the plunger inthe case to compress the springs and reset the trigger.

KENNETH B. CONiNER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Davenport Jan. 22, 1946

